Long Range Discussion: Spring 2021

[Nash_LSU]

Unfortunately, even in the near-term going into meteorological spring, the signs are there that flooding may become a widespread issue for much of the region due to completely saturated soils.

There is relatively strong agreement that 3-5in of rainfall is likely over the next 2 weeks.

While this winter has been damp, it has mostly been light rain, unlike the last couple years that had pretty substantial volumes of rain. The local reservoirs and rivers are still at their low winter levels. That puts us at a much better advantage going in to spring than the last couple of years. That said, when I see people start throwing out 2011 spring analogs, I get a little nervous. My background is in water management in SE Louisiana, and 2011 was a doozy for us because of all the rain in the Ohio watershed. That was the year we saw Morganaza opened for only the second time. Those of us south of Old River Control were sweating bullets during that flood. It took the lower Mississippi system to the max. 

[JayCee]

From the look of the long range EURO, I think we're about to get a substantial volume of rain over the next two weeks.  Tennessee seems to be ground zero for the heaviest amounts of rain in the whole lower 48, even outdoing the mountains of the Pacific Northwest.  March could see some significant flooding problems for our area if it verifies. 

EDIT:  MRX sees the signs of some hydro problems by early next week.

While confidence is low on the track and
placement of associated frontal boundaries with this system, the
overall consensus is for broad southerly flow and deep Gulf moisture
advection. Ensemble means and deterministic guidance all point
towards PWAT values reaching near to above 1.0" Sunday and into
Monday, which is climatologically significant for this time of year.
Based on BNA sounding climatology, these values are near to above
daily max PWAT values for late Feb/early Mar. Although confidence is
very limited at this temporal scale, these indications may allow for
persistent, potentially heavy rainfall locally. With antecedent
rainfall expected, very general HWO wording for at least isolated
flooding will be utilized to give everyone a heads up. This system
will certainly be something to watch in the coming days for
potential flooding.

[Nash_LSU]

...and as soon as I open my big mouth about having capacity in the system, you post a 6"-12" rainfall map. I should just keep my mouth shut.   

[JayCee]

Today's run of the Euro is showing a similar solution of heavy rain starting sometime early Friday and lasting into next week. although totals aren't quite as extreme as the last run (but bad enough).  It appears a front moves in and decides to make a home in the TN Valley.  Waves of low pressure with heavy rain and even rounds of thunderstorms move through repeatedly.  The entire state west to east is gets soaked multiple times.  Reservoirs will be filling up fast, similar to the last several springs, if it plays out as shown. 

[Crockett]

As Nash_LSU mentioned, our reservoirs should be pretty well equipped to handle a deluge of rainfall right now, compared to where we were at by this point the past several years. Here on the northern plateau, we've received only a little more than 2.5" of rain so far this month compared to 10-12" of rain each of the past three Februarys.

I bet we'll be dealing with some flash flooding this weekend, though. Grounds are super saturated and there's a lot of rain coming our way between these next two systems...especially the second system Sunday-Monday, if it pans out.

[JayCee]

I've had about 4.5" of rain this month, thanks in part to the heavy rain that fell when areas west of here were seeing snow.  Nothing close to last February.  I suppose the colder pattern has reduced the amount of moisture available compared to the last few years.  One more reason to prefer a cold winter over a mild & super wet one. March may be a different story as the cold retreats. 

[Navywxman]

...and as soon as I open my big mouth about having capacity in the system, you post a 6"-12" rainfall map. I should just keep my mouth shut.   

Lol, it's all your fault.

But yes, we have good reservoir pool capacity it appears, but this melting will completely saturate the ground in much of the watershed, which will lead to high runoff due to dormant vegetation still.

[Matthew]

My yard is completely saturated.  Nothing but water seeping up as we walk on it.  I would think 5

[Navywxman]

My yard is completely saturated.  Nothing but water seeping up as we walk on it.  I would think 5